Description

• Acute abscess of a preexisting preauricular sinus
• Preauricular sinus
  • First described by Van Heusinger in 1864
  • One of the most common congenital abnormalities of the head and neck region
  • Sporadic and inherited occurrence
• Synonym(s): infected preauricular sinus; infected ear pit; infected preauricular pit

Epidemiology

• Males and females equally affected
• Preauricular sinus forms during antenatal period and present at birth but can become apparent at an older age.

Incidence

• No defined incidence of preauricular abscess
• Preauricular sinus incidence in the United States is 0.1–0.9%, 0.9% in England, 1.6–2.5% in Taiwan, and 4–10% in some areas of Africa.

Prevalence
No defined prevalence of preauricular abscess

Etiology and Pathophysiology

• Etiology
  • Most commonly: Staphylococcus spp.
  • Less commonly: Streptococcus spp.
• Pathophysiology
  • Three theories for preauricular sinus formation: defective fusion of the six auricular hillocks resulting in preauricular sinus; remnants of incomplete closure of the dorsal part of the first pharyngeal groove; and isolated ectodermal folding during auricular development
  • Abscesses are caused by obstruction of these preauricular sinus openings leading to fluid collection within sinus.

Genetics

• Autosomal dominant pattern with incomplete penetrance and variable expression
• Rarely associated with branchiootorenal (BOR) syndrome (autosomal dominant disorder)

Risk Factors

• Poor hygiene
• Preexisting preauricular sinus
• Epidermal cysts
• Pseudocysts of the auricle
• Calculi

Commonly Associated Conditions

Preauricular sinus is rarely associated with hemifacial microsomia and microtia.